The present invention relates to booster circuits implemented with MOS (metal oxide semiconductor) type integrated circuits.
Heretofore, a variety of such circuits have been proposed. An example of a conventional booster circuit is shown in FIG. 1. In FIG. 1, reference numeral 1 designates an input terminal to which a signal .phi..sub.A to be boosted is applied, reference numeral 2 a load capacitor for the signal .phi..sub.A, 3 an input terminal to which a boost signal .phi..sub.B is applied, and 4 a boost capacitor.
In the circuit shown in FIG. 1, a voltage .phi..sub.A which is to be boosted in response to the boost signal .phi..sub.B as shown in FIG. 2B is represented by ##EQU1## as shown in FIG. 2A where C.sub.1 is the capacitance of the load capacitor 2, C.sub.2 is the capacitance of the boost capacitor 4 and V is the voltage of an external voltage source. Accordingly, assuming that the voltage V is set externally, the boost range of the voltage is defined by the capacitance of the boost capacitor 4. That is, as is clear from the above expression, in the case where the load capacitor C.sub.1 is relatively large, the capacitance value of the boost capacitor C.sub.2 must also accordingly be large. Due to this fact, if it is desired that the large load capacitor 2 be driven by the signal .phi..sub.A at a high rate, it is necessary to provide the signal .phi..sub.A with a high driving ability for driving the boost capacitor 4. To provide a high driving ability requires a great deal of chip area for a driving circuit on an integrated circuit chip and results in a high power consumption for the driving circuit.